Semiconductor devices such as integrated circuits are generally fabricated by the repeated application of a photolithographic process. A photosensitive material is applied to the surface of a semiconductor substrate, which may include layers of dielectric materials, polycrystalline silicon, and various metals, and a radiation source is used to transfer the pattern of a lithographic mask or reticle onto the photosensitive material. The patterned photosensitive material is then used as a process mask to process the semiconductor substrate or one of the layers on the substrate. The process mask may be used, for example, as an etch mask or as an ion implantation mask.
As the number of individual devices incorporated in the design of a semiconductor integrated circuit increases, there is a growing need to decrease the minimum feature size, that is, the minimum width, the minimum space between individual elements of the devices, the minimum widths of holes or vias, and the like. As the minimum feature size decreases, especially when the minimum feature size is less than the wavelength of the radiation source, it becomes increasingly difficult to adequately resolve the features because of diffraction and interference effects. Optical distortion causes a loss of the anticipated one-to-one correspondence between the image on the mask and the image created in the patterned photosensitive material. While extreme ultraviolet (EVU) lithography and electron-beam lithography may be used to pattern photoresists with small feature size, such processes are complex and very expensive.
Accordingly, it is desirable to provide improved methods for fabricating semiconductor devices that have small feature sizes. In addition, it is desirable to provide methods for etching small features into a subject material layer. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.